Recently, attention has been drawn to vehicles run by drive power from an electric motor, for example, hybrid vehicles, fuel cell vehicles, electric vehicles, etc., as environmental protection measures. Such a vehicle is equipped with a battery, a capacitor, or the like for storing electric power to be supplied to an electric motor.
Japanese Patent Application Publication No. JP-A-7-117489 discloses a battery mounting structure for an electric vehicle which allows a reduction of the space in a cabin which is taken up by the battery. The battery mounting structure for an electric vehicle described in Japanese Patent Application Publication No. JP-A-7-117489 is a structure for mounting a battery in an electric vehicle that has side members (side frames) that extend in the longitudinal direction of the vehicle. In this battery mounting structure, a plurality of vertically stacked batteries are disposed between the wheelbase portions of the side members so that the batteries protrude in the up-down direction with respect to the side members. A battery case that houses the batteries is mounted near kick-up portions of the side members by a vertically arranged pair of mounting members that sandwich the side members.
According to the structure disclosed in this patent application publication, since a plurality of vertically stacked batteries are disposed so as to protrude in the up-down directions from the side members, it is possible to reduce the space taken up by the battery in the cabin. Furthermore, since batteries, which are heavy in weight, are disposed between the wheelbase portions of the side members extending in the longitudinal direction of the vehicle, the center of gravity of the electric vehicle does not become one-sided toward the front or rear of the vehicle body. This allows securement of a large cabin space and utilization of an ample space, and makes it possible to improve the steerability. Furthermore, the battery case is mounted on the side members by a vertical pair of mounting members that are provided so as to sandwich the side members. By mounting the battery case in this manner, the side members are reinforced.
However, since the battery case is firmly mounted on the side members in the structure described in the aforementioned publication, the structure has the following problems. If a side member is squeezed and deformed, for example, in the case where the vehicle is rear-ended by another vehicle, the battery case will likely be deformed together with the side members, and the battery case and the batteries therein may possibly break.